Processes for catalytic conversion of plastic wastes to light olefins

Abstract

Provided herein are processes for conversion of a plastic waste to ethylene and propylene including heating a plastic waste to provide a liquid plastic waste and hydrocracking the liquid plastic waste with hydrogen and a hydrocracking catalyst to produce a hydrocracked product comprising at least 70 wt.% ethane, less than 5 wt.% aromatics, propane and butane.

Description

2024EM157-USPROCESSES FOR CATALYTIC CONVERSION OF PLASTIC WASTES TO LIGHT OLEFINSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to US Provisional Application No. 63 / 733781 filed December 13, 2024, the disclosure of which is incorporated herein by reference.FIELD

[0002] The present disclosure related to combining mild pyrolysis and catalytic hydrocracking of plastic waste to produce a hydrocracked product that can be converted to light olefins with increased yield.BACKGROUND

[0003] There is increasing demand from society and policy / regulatory drivers for more circular plastics. Converting difficult-to-recycle and highly heterogeneous waste plastics into building blocks, from which virgin polymers can be made, is an attractive approach. The state- of-the-art advanced recycling technology is thermal pyrolysis, either in a stand-alone unit or via co-processing.

[0004] Another approach is first converting plastics to pyoil via mild pyrolysis, followed by cracking of pyoil to light olefins. However, light olefin yield from these technologies is typically modest (e.g., approximately 45 wt.%).SUMMARY

[0005] Provided herein are processes for conversion of a plastic waste to ethylene and propylene comprising the steps of heating the plastic waste to provide a liquid plastic waste and hydrocracking the liquid plastic waste with hydrogen and a hydrocracking catalyst to produce a hydrocracked product comprising at least 70 wt.% ethane, less than 5 wt.% aromatics, propane and butanes. Ethane is separated from the hydrocracked product and converted to ethylene. Propane is separated from the hydrocracked product and converted to propylene. Butanes and aromatics are saturated with hydrogen and a saturating catalyst to provide a saturated product. The saturated product is recycled and combined with the liquid plastic waste to make additional olefins.

[0006] Also provided herein are processes for conversion of a plastic waste comprising the steps of heating the plastic waste to a temperature of 550°C or less to provide a pyoil, and hydrocracking the pyoil with hydrogen in the presence of a hydrocracking catalyst selected from the group of Pt / ZSM-5, Pt / MOR, Pt / FAU, and Pt / BEAat a pressure between 100 psig and2024EM157-US2,000 psig of H2, and at a temperature between 350°C and 600°C. The plastic waste decomposes to produce a hydrocracked product comprising greater than 50 wt.% ethane, greater than 15 wt.% propane, less than 5 wt.% aromatics and butanes. The ethane is steam cracked to provide ethylene. The propane is dehydrogenated catalytically to provide propylene. The butanes and aromatics are saturated at a pressure of between 100 psig and 2,000 psig of H2, at a temperature between 50°C and 350°C in the presence of a saturating catalyst selected from Pt-Pd, Pt-Ir, or Ir-Rh to provide a recycle feed stream for hydrocracking with the pyoil.BRIEF DESCRIPTION OF DRAWINGS

[0007] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, wherein:

[0008] FIG. l is a chart showing comparative data of product yields versus carbon number for a flash pyrolysis (“FP”) of linear low-density polyethylene (“LLDPE”) and a mild pyrolysis (“MP”) of LLDPE as described in Example 1.

[0009] FIG. 2 is a chart showing comparative data of product yields versus carbon number for a flash pyrolysis of LLDPE followed by acid cracking (“AC”) in the absence of hydrogen as described in Example 2.

[0010] FIG. 3 a is chart showing comparative data of product yields for a mild pyrolysis of LLDPE followed by hydrocracking LLDPE in presence of hydrogen and a hydrocracking catalyst as described in Example 3.

[0011] FIG. 4 is a chart showing comparative data of product yields for a mild pyrolysis of various plastics followed by hydrocracking in the presence of hydrogen and a hydrocracking catalyst as described in Example 4.DETAILED DESCRIPTION

[0012] Before the present compounds, components, compositions, and / or methods are disclosed and described, it is to be understood that unless otherwise indicated this disclosure is not limited to specific compounds, components, compositions, reactants, reaction conditions, ligands, catalyst structures, or the like, as such may vary, unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing different embodiments and is not intended to be limiting.

[0013] All numerical values within this detailed description and claims should be considered modified by “about” or “approximately” the indicated value to account for experimental error and variations.

[0014] For the purposes of this disclosure, the following definitions will apply:2024EM157-US

[0015] As used herein, the terms “a” and “the” as used herein are understood to encompass the plural as well as the singular.

[0016] As provided herein, a reference to a “Cx” fraction, stream, portion, feed, or other quantity is defined as a fraction (or other quantity) where 50 wt.% or more of the fraction corresponds to hydrocarbons having “x” number of carbons. When a range is specified, such as “Cx-Cy,” 50 wt.% or more of the fraction corresponds to hydrocarbons having a number of carbons between “x” and “y”. A specification of “Cx+” (or “Cx-”) corresponds to a fraction where 50 wt.% or more of the fraction corresponds to hydrocarbons having the specified number of carbons or more (or the specified number of carbons or less).

[0017] The term “plastic waste” means and includes any classification of consumer waste plastics, post-consumer wastes and post-industrial wastes.

[0018] As described herein, the term “polyolefin” refers to and includes high-density polyethylene (“HDPE”), low-density polyethylene (“LDPE”), linear low-density polyethylene (“LLDPE”), polyethylene (“PE”), and polypropylene (“PP”), or mixtures thereof. Polyolefin further includes co-polymers of various olefins, such as butene, hexenes, and / or any other olefins suitable for polymerization. As used herein, the term “polyolefin” further includes polyethylene terephthalate (“PET”), polystyrene (“PS”), poly(vinyl chloride) (“PVC”), poly(vinyl dichloride) (“PVDC”).

[0019] The term “pyoil” means and includes liquids derived from plastic waste comprising HDPE, LDPE, LLDPE, PE, PP, PET, PS, PVC, PVDC or a mixture thereof.

[0020] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited and ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0021] Described herein are processes that improve light olefin yield. In the present processes, it has been discovered that hydrocracking liquid plastic waste with certain hydrocracking catalysts maximize light alkane yields such as ethane and propane (more desirably ethane). Surprisingly, the present process produces more ethane than propane, butanes and aromatics.2024EM157-US

[0022] The present process for conversion of plastic waste to ethylene and propylene includes the steps of heating a plastic waste to provide a liquid plastic waste. In an embodiment, the plastic waste comprises polyethylene, polypropylene, polystyrene, poly(ethylene terephthalate), poly(vinyl chloride), poly (vinyl dichloride), or a mixture thereof. The plastic waste is heated at a temperature of between 250°C and 550°C.

[0023] The liquid plastic waste is hydrocracked with hydrogen and a hydrocracking catalyst. Hydrocracking operates at a liquid hourly space velocity of between 0.1 g and 10 g feed / g catalyst / hour. The hydrocracking catalyst comprises a metal function and an acid function. The metal function comprises Pt, Pd, Ir, Ni, Rh, Ir, Ru, or a combination thereof and the acid function comprises a zeolite selected from MFI, MOR, FAU, MWW, BEA, or a combination thereof. In an embodiment, the hydrocracking catalyst is selected from the group ofPt / MFI, Pt / MOR, Pt / FAU, Pt / BEA, or Pt-Ir / MFI.

[0024] In an embodiment, the liquid plastic waste is a pyrolysis oil (referred herein as a “pyoil”). In an embodiment, the pyoil is hydrotreated with a hydrotreating catalyst to remove halogen, oxygen, and nitrogen from the pyoil at a pressure between 100 psig and 2,000 psig of H2, a temperature between 350°C and 550°C at a liquid hourly space velocity between 0.1 g and 10 g pyoil / g catalyst / hour. The hydrotreating catalyst comprises CoMo, CoW, NiMo, NiW, Fe, Pt, Ru, Au, Rh, Ir, or a combination thereof, optionally supported on catalyst support comprising alumina, silica, silica-alumina, titania, zirconia, carbon, or a combination thereof.

[0025] The hydrocracked product (product produced by hydrocracking) comprises at least 70 wt.% ethane, less than 5 wt.% aromatics, propane and butane. Alternatively, the hydrocracked product comprises greater than 50 wt.% ethane, greater than 15 wt.% propane, less than 5 wt.% aromatics and butanes. In the present processes, ethane is separated from the hydrocracking product and converted to ethylene by steam cracking or dehydrogenation processes. Propane is separated from the hydrocracked product and converted to propylene via dehydrogenation process. In an embodiment, ethane is steam cracked to provide ethylene. In an embodiment, propane is dehydrogenated catalytically to provide propylene. Butanes and aromatics are saturated with hydrogen and a saturating catalyst to provide a saturated product. The saturated product is recycled and combined with the liquid plastic waste to make additional olefins.

[0026] In the present processes, butanes and aromatics are saturated at a pressure of between 100 psig and 2,000 psig of H2, a temperature of between 50°C and 350°C and a liquid hourly space velocity between 0.1 g and 10 g feed / g catalyst / hour. In an embodiment, the saturating catalyst is selected from the group of Pt, Pd, Ir, Rh, Ru, or a combination thereof,2024EM157-US optionally supported on catalyst support comprising alumina, silica, silica-alumina, titania, zirconia, carbon, or a combination thereof.Processing of Plastic Waste

[0027] Consumer waste plastics or “plastic waste” are classified and include polyethylene terephthalate waste (plastics recycle classification type 1), high density polyethylene waste (plastics recycle classification type 2), polyvinyl chloride waste (plastics recycle classification type 3), low density polyethylene waste (plastics recycle classification type 4), polypropylene waste (plastics recycle classification type 5), polystyrene waste (plastics recycle classification type 6) and other polymer waste (plastics recycle classification type 7).

[0028] In recycling plastic waste, polyethylene waste and polypropylene waste are often individually sorted from the plastic waste and sometimes sorted together from the plastic waste. See e.g., US Pub. App. No. 2021 / 0332299,

[0042] , Undesirable plastic materials such as multilayer films or composites and / or compounded wastes such as rubber tires can be mechanically sorted from the feed stream with near infrared spectroscopy (NIR), laser or x-ray technologies. Other undesirable materials can include stones, metals and other noncombustible hard materials which can be removed by mechanical means. For example, ferrous metals can be removed by a magnet.

[0029] To prepare solids, the solid polymers / polyolefms can be crushed, chopped, ground, or otherwise physically processed to reduce the median particle size to 3.0 cm or less, or 2.5 cm or less, or 2.0 cm or less, or 1.0 cm or less, such as down to 0.01 cm or possibly still smaller. For determining a median particle size, the particle size is defined as the diameter of the smallest bounding sphere that contains the particle.

[0030] In the present processes, a feed stream of a plastic waste (sometimes referred to as “plastic feedstock”) is heated to a temperature that produces a liquid plastic waste. By way of example, the plastic waste can be process by thermal pyrolysis to produce a pyrolysis plastics effluent stream. In an embodiment, the plastic feedstock is pyrolyzed (heated in the absence of oxygen) using one or more of various pyrolysis methods including fast pyrolysis and other pyrolysis methods such as vacuum pyrolysis, slow pyrolysis, and the like. Fast pyrolysis is an intense, short duration process that can be carried out in a variety of pyrolysis reactors such as fixed bed pyrolysis reactors, fluidized bed pyrolysis reactors, circulating fluidized bed reactors, or other pyrolysis reactors capable of fast pyrolysis. Fast pyrolysis includes rapidly imparting a relatively high temperature to feedstocks for a very short residence time, typically about 0.5 seconds to about 0.5 minutes, and then rapidly reducing the temperature of the pyrolysis effluent before chemical equilibrium can occur. By this approach, the structures of polymers2024EM157-US are broken into reactive chemical fragments that are initially formed by depolymerization and volatilization reactions, but do not persist for any significant length of time.

[0031] The heating and cooling of products produced in a plastic waste reactor (a reactor sometimes referred to as a “pyrolyzer” or a “pyrolysis unit”) can be performed in any convenient manner. For example, at least a portion of the heating of the plastic waste feedstock to the pyrolysis temperature can be performed at a heating rate of 100°C per second or more, or 200°C per second or more, such as up to l,000°C per second or possibly still faster. WO 2020 / 252228 Al

[0033] ,

[0034] ,

[0035] and

[0038] incorporated by reference; US Pub. No. 2021 / 0130700 Al,

[0171] -

[0177] .

[0032] Both operating temperature of the plastic waste reactor and reaction time depend in part on the desired products. Higher temperatures increase selectivity for light gases such as ethylene and propylene, while lower temperatures increase selectivity to liquids (“Pyoil”). Shorter reaction times (at or above 500°C) reduce or minimize formation of coke. In an embodiment, the reaction time can correspond to 0.1 seconds to 6.0 seconds, or 0.1 seconds to 5.0 seconds, or 0.1 seconds to 1.0 seconds, or 1.0 seconds to 6.0 seconds, or 1.0 seconds to 5.0 seconds.

[0033] To control light gas and liquids yield, a diluent steam is fed into the reactor. Steam also serves as a fluidizing gas. The weight ratio of steam to plastic feedstock can be between 0.3:1 to 10: 1.

[0034] The liquid plastic waste in the form of pyoil is then optionally cooled to below 500°C at the end of the reaction time. An effluent stream from the plastic waste reactor typically includes the heat carrier particles, the diluent gas stream, a pyrolyzed product, and other products such as olefin and oil. Most notably, simpler lighter hydrocarbon molecules, including ethylene and propylene, are often generated at varying fractions within the effluent stream.

[0035] In an embodiment, the plastic feedstock is fed into a thermal pyrolyzer and heated to a temperature between 500°C and 900°C for a given reaction time. The plastic waste reactor melts plastic waste in a fluidized flow, or in a transport or pneumatic conveyance flow, with a dilute phase of heat carrier particles. A quasi-dense bed of plastic and heat carrier particles undergo pyrolysis at the bottom of the plastic waste reactor. Gaseous pyrolyzed plastic and heat carrier particles flow upwardly upon size reduction due to pyrolysis. Alternatively, the plastic waste reactor can be a continuous stirred tank reactor, a rotary kiln, or an auger reactor. In an embodiment, the plastic waste reactor employs an agitator.2024EM157-US

[0036] In an embodiment, the plastic waste reactor is a fluidized bed where the plastic feedstock is mixed with heated fluidizing particles. Sand is an example of a suitable type of fluidizing particle for the fluidized bed. During operation, sand (or another type of heat transfer particle) can be passed into a regenerator to burn off coke and heat the particles. Often additional heat is supplied in the regenerator to compensate for the coke in the process. Typically, the heated particles are mixed with the plastic waste feedstock prior to entering the reactor. By heating the heat transfer particles to a temperature above the desired pyrolysis temperature, the heat transfer particles can provide at least a portion of the heat needed to achieve the pyrolysis temperature. For example, the heat transfer particles can be heated to a temperature that is greater than the desired pyrolysis temperature by 100°C or more. Optionally, if the plastic feedstock, sand, and fluidizing steam do not provide sufficient material to form a fluidized bed, additional fluidizing gas can be added, such as additional nitrogen. However, this might cause a corresponding increase in the volume of gas flow that needs to be handled during product recovery.

[0037] Upon exiting from the plastic waste reactor, the heat transfer particles are separated from the vapor portions of the effluent using a cyclone or another solid / vapor separator. Such a separator can also remove any other solids present after pyrolysis. It is noted that separation using a cyclone separator can result in an increase in N2 in the steam cracker effluent, which can make product recovery more challenging. Optionally, in addition to a cyclone or other primary solid / vapor separator, one or more filters can be included at a location downstream from the cyclone to allow for removal of fine particles that become entrained. As provided herein, the production of polymer-grade olefin fractions is most desirable. US Pub. No. 2022 / 0195309.Hydrocracking Liquid Plastic Waste

[0038] Generally, hydrocracking is a versatile catalytic process that has been used to upgrade petroleum feedstock by adding hydrogen, removing impurities, and cracking hydrocarbons to a desired boiling range. Hydrocracking is characterized by the fact that a hydrocracking product has a lower molecular weight than a hydrocracking feedstock. Hydrocracking requires conversion of a variety of types of molecules. Exemplary hydrocracking processing is described in US Pat. No. 8,932,454 and US Pat. No. 9,309,472.

[0039] Historically, the hydrocracking feedstock ranges from heavy vacuum gas oils and coker gas oils to atmospheric gas oils. Hydrocracking products usually range from heavy diesel to light naphtha. However, hydrocracking is a suitable process for generating products that meet or exceed many environmental regulations.2024EM157-US

[0040] Hydrocrackers are operated at a variety of conditions depending on many factors such as type of feed, desired cycle length, expected product slate. Typically, a hydrocracker will operate at liquid hourly space velocity (LHSV) of 0.5 g to 2.0 g feed / g catalyst / hour, H2 circulation of 5,000 SCFB to 10,000 SCFB (850 to 1,700 Nm3 / m3), H2 partial pressure of 1,500 psia to 2,000 psia (103 bars to 138 bars), and start of run (“SOR”) temperatures ranging between 675°F and 725°F (or 357°C to 385°C).

[0041] The hydrocracker feedstock is often based on a boiling range of the feedstock. One option for the boiling range is to use an initial boiling point for the feedstock and / or a final boiling point for the feedstock. Another option, which in some instances may provide a more representative description of a feedstock, is to characterize the feedstock based on the amount of the feed that boils at one or more temperatures. For example, a “T5” boiling point for a feed is defined as the temperature at which 5 wt.% of the feed will boil off. Similarly, a “T95” boiling point is a temperature at which 95 wt.% of the feed will boil, while a “T99.5” boiling point is a temperature at which 99.5 wt.% of the feed will boil. US Pat. No. 9,309,472, Col. 5. Is. 42 to 53.

[0042] Typical hydrocracker feedstocks include, for example, feeds with an initial boiling point of at least about 650°F (343°C), or at least about 700°F (371°C), or at least about 750°F (399°C). The amount of lower boiling point material in the feedstock may impact the total amount of diesel generated as a side product. Alternatively, the feedstock may be characterized using a T5 boiling point, such as a feedstock with a T5 boiling point of at least about 650°F (343°C), or at least about 700°F (371°C), or at least about 750°F (399°C). Typical hydrocracker feedstocks include, for example, feedstock having a final boiling point of about l,150°F (621°C), or about l,100°F (593°C) or less, or about l,050°F (566°C) or less. Alternatively, the hydrocracker feedstock may be characterized using a T95 boiling point, such as a feed with a T95 boiling point of about l,150°F (621°C), or about l,100°F (593°C) or less, or about l,050°F (566°C) or less. US Pat. No. 9,309,472, Col. 5, 1. 54 to Col. 6, 1. 1.

[0043] Hydrocracking conditions depend on the desired level of conversion, the level of contaminants in the input feed to the hydrocracking stage, and potentially other factors. For example, hydrocracking under sour conditions, such as conditions where the sulfur content of the input feed to the hydrocracking stage, is at least 500 wppm, can be carried out at temperatures of about 550°F (288°C) to about 840°F (449°C), hydrogen partial pressures of from about 250 psig to about 5,000 psig (1.8 MPag to 34.6 MPag), liquid hourly space velocities of from 0.05 h-1to 10 h-1, and hydrogen treat gas rates of from 35.6 in / m3to 1781 m3 / m3(200 SCF / B to 10,000 SCF / B). In other embodiments, the conditions can include2024EM157-US temperatures in the range of about 600°F (343°C) to about 815°F (435°C), hydrogen partial pressures of from about 500 psig to about 3,000 psig (3.5 MPag - 20.9 MPag), liquid hourly space velocities of from about 0.2 h1to about 2 h1and hydrogen treat gas rates of from about 213 m3 / m3to about 1,068 m3 / m3(1,200 SCF / B to 6,000 SCF / B). US Pat. No. 9,309,472, Col. 12, ls.29 to 48.

[0044] Hydrocracking performed under non-sour conditions can be performed under similar conditions used for sour conditions, or the conditions can be different. Alternatively, non-sour hydrocracking can have less severe conditions than similar hydrocracking operating under sour conditions. Suitable hydrocracking conditions can include temperatures of about 550°F (288°C) to about 840°F (449°C), hydrogen partial pressures of from about 250 psig to about 5,000 psig (1.8 MPag to 34.6 MPag), liquid hourly space velocities of from 0.05 h1to 10 h1, and hydrogen treat gas rates of from 35.6 m3 / m3to 1,781 m3 / m3(200 SCF / B to 10,000 SCF / B). In other embodiments, the conditions can include temperatures in the range of about 600°F (343°C) to about 815°F (435°C), hydrogen partial pressures of from about 500 psig to about 3,000 psig (3.5 MPag-20.9 MPag), liquid hourly space velocities of from about 0.2 h1to about 2 h-1and hydrogen treat gas rates of from about 213 m3 / m3to about 1,068 m3 / m3(1,200 SCF / B to 6,000 SCF / B).

[0045] Typically, hydrocracking catalysts promote paraffin cracking and reduce the quality of the intermediate hydrocarbon product for production of paraffinic diesel, high quality base stocks and / or wax. As provided herein, the hydrocracking catalyst includes, but is not limited to, a zeolitic base selected from zeolite Beta, zeolite X, zeolite Y, faujasite, ultrastable Y (USY), dealuminized Y (Deal Y), Mordenite, ZSM-3, ZSM-4, ZSM-18, ZSM-20, ZSM-48, and combinations thereof, which zeolitic base can advantageously be loaded 20 with one or more active metals (e.g., either (i) a Group 8 - 10 noble metal such as platinum and / or palladium or (ii) a Group 8 - 10 non-noble metal such nickel, cobalt, iron, and combinations thereof, and a Group 6 metal such as molybdenum and / or tungsten). Zeolitic materials include materials having a recognized zeolite framework structure, such as framework structures recognized by the International Zeolite Association. Such zeolitic materials can correspond to silicoaluminates, silicoaluminophosphates, aluminophosphates, and / or other combinations of atoms that are used to form a zeolitic framework structure.

[0046] Zeolites can be classified as having small, medium, large, and extra-large pore structures for pore windows delimited by 8, 10, 12, and more than 12 T-atoms, respectively. Extra-large pore zeolites (>12R) include, for example, AET (14R, e.g., ALPO-8), SFN (14R, e.g., SSZ-59), VFI (18R, e.g., VPI-5), CLO (20R, e.g., cloverite), and ITV (30R, e.g., ITQ-37)2024EM157-US framework type zeolites. Extra-large pore zeolites generally have a free pore diameter of larger than about 0.8 nm. Large pore zeolites (12R) include, for example, LTL, MAZ, FAU, EMT, OFF, MTW, *BEA, MOR, and SFS framework type zeolites, e.g., mazzite, offretite, zeolite L, zeolite Y, zeolite X, omega, ZSM-2, ZSM-12, zeolite T, Beta, and SSZ-56. Large pore zeolites generally have a free pore diameter of 0.6 nm to 0.8 nm. Medium (or intermediate) pore size zeolites (10R) include, for example, MFI, MEL, *MRE, EUO, MTT, MFS, AEL, AFO, HEU, FER, MWW, and TON framework type zeolites, e.g., ZSM-5, ZSM-11, ZSM-48, ZSM-22, ZSM-23, ZSM-35, MCM-22, MCM-49, silicalite- 1 , and silicalite-2. Medium pore size zeolites generally have a free pore diameter of 0.45 nm to 0.6 nm. Small pore size zeolites (8R) include, for example, CHA, SSZ-13, RTH, ERI, KFI, LEV, and LTA framework type zeolites, e.g., ZK-4, SAPO-34, SAPO-18, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite.

[0047] In addition to zeolitic materials, other types of crystalline acidic support materials can also be suitable. Optionally, a zeolitic material and / or other crystalline acidic material are mixed or bound with other metal oxides such as alumina, titania, and / or silica. Hydrocracking catalysts are described in US Pub. No. 2015 / 0715555. For example, hydrocracking catalysts with acidity inclusive of phosphate and fluoride modification of an alumina (AI2O3) support are ideal appropriate to produce a high-quality base stock by hydro-dealkylation but have value to fuels applications such as production of paraffinic diesel. Acidity of a catalyst can be measured by uptake of a base probe molecule such as ammonia, cracking activity of a model feed such as hexane under a set of standard conditions.

[0048] A non-limiting example of a parameter for inferring acidity is the cracking and isomerization tendency of a catalyst by the Alpha value test. The Alpha value test is a measure of the cracking activity of a catalyst and is described in US Pat. No. 3,354,078 and in the Journal of Catalysis, NA, p. 527 (1965); v.6, p. 278 (1966); and v.61, p. 395 (1980), each incorporated herein by reference as to that description. The experimental conditions of the test referenced herein include a constant temperature of 538°C and a variable flow rate as described in detail in the Journal of Catalysis, v.61, p. 395. The “Alpha Value” is the cracking rate of a feed in reference to a standard sample of silica alumina. Catalysts that are conventionally believed to be suitable for hydrocracking activity can have Alpha values of at least about 25, or at least about 50, or at least about 100. Such catalysts can include amorphous catalysts, such as amorphous silica-alumina or alumina supports or additives and zeolites. Under certain reaction conditions, catalyst acidity (Alpha value of at least about 25) can lead to unselective wax isomerization and / or wax cracking diminishing base stock / wax value of the VGO range2024EM157-US product. By contrast, a paraffinic diesel product produced with a high acidity catalyst can have improved cold flow properties (i.e., Cloud Point by ASTM D2500-17, Pour Point by ASTM D97-17) because of isomerization and paraffin cracking.

[0049] Hydrocracking catalysts often contain sulfided base metals on acidic supports, such as amorphous silica alumina, cracking zeolites or other cracking molecular sieves such as USY, or acidified alumina. In an embodiment, the hydrocracking catalyst can include at least one molecular sieve, such as a zeolite. Often these acidic supports are mixed or bound with other metal oxides such as alumina, titania or silica. Non-limiting examples of supported catalytic metals for hydrocracking catalysts include nickel, nickel-cobalt-molybdenum, cobaltmolybdenum, nickel-tungsten, nickel-molybdenum, and / or nickel-molybdenum-tungsten. Additionally, or alternately, hydrocracking catalysts with noble metals can also be used. Nonlimiting examples of noble metal catalysts include those based on platinum and / or palladium. Support materials which may be used for both the noble and non-noble metal catalysts can comprise a refractory oxide material such as alumina, silica, alumina-silica, kieselguhr, diatomaceous earth, magnesia, zirconia, or combinations thereof, with alumina, silica, alumina- silica being the most common (and preferred, in one embodiment). US Pat. No. 9,309,472, Col. 11, 1. 62 to Col. 12, 1. 28, incorporated herein by reference.

[0050] As described above, the hydrocracking catalyst can include a large pore molecular sieve that is selective for cracking branched hydrocarbons and / or cyclic hydrocarbons. Zeolite Y, such as ultrastable zeolite Y (USN) is an example of a zeolite molecular sieve that is selective for cracking of branched hydrocarbons and cyclic hydrocarbons. See US Pat. No. 8,932,454, Col. 3. 1.4 to Col. 4, 1.5. The silica to alumina ratio in a USY zeolite can be at least about 10, such as at least about 15, or at least about 25, or at least about 50, or at least about 100. The unit cell size for a USY zeolite can be about 24.50 Angstroms or less, such as about 24.45 Angstroms or less, or about 24.40 Angstroms or less, or about 24.35 Angstroms or less, such as about 24.30 Angstroms.

[0051] In the present process, the liquid plastic waste such as pyoil is hydrocracked with hydrogen and a hydrocracking catalyst. Hydrocracking operates at a liquid hourly space velocity of between 0.1 and 10 g feed / g catalyst / hour. The hydrocracking catalyst comprises a metal function and an acid function. The metal function comprises Pt, Pd, Ir, Ni, Rh, Ru, or a combination thereof and the acid function comprises a zeolite selected from MFI, MOR, FAU, MWW, BEA, or a combination thereof. In an embodiment, the hydrocracking catalyst is selected from the group of Pt / MFI, Pt / MOR, Pt / FAU, Pt / BEA, or Pt-Ir / MFI.2024EM157-USHydrotreating

[0052] Optionally, the liquid plastic waste can be hydrotreated with a hydrotreating catalyst to remove halogen, oxygen, and nitrogen from the liquid plastic waste (e.g., pyoil) at a pressure between 100 psig and 2,000 psig of H2, a temperature between 350°C and 550°C at a liquid hourly space velocity between 0.1 and 10 g pyoil / g catalyst / hour. In an embodiment, the hydrotreating catalyst comprises C0M0, CoW, NiMo, NiW, Fe, Pt, Ru, Au, Rh, Ir, Ru or a combination thereof, optionally supported on catalyst support comprising alumina, silica, silica-alumina, titania, zirconia, carbon, or a combination thereof.

[0053] Hydrotreating conditions can include temperatures of about 200°C to about 450°C, or about 315°C to about 425°C and pressures of about 250 psig (1.8 MPag) to about 5,000 psig (34.6 MPag) or about 300 psig (2.1 MPag) to about 3,000 psig (20.8 MPag). For hydrotreating, liquid hourly space velocities (LHSV) can range from about 0.1 hr1to about 10 hr’1. Hydrogen treatment rates include about 200 scf / B (35.6 m3 / m3) to about 10,000 scf / B (1781 m3 / m3), or about 500 (89 m3 / n) to about 10,000 scf / B (1781 m3 / m3).

[0054] Hydrotreating is typically used to reduce the sulfur, nitrogen, and aromatic content of a feed. The hydrotreating catalyst (a conventional hydrotreating catalyst) comprises at least one Group VIII non-noble metal (Columns 8-10 of IUPAC periodic table) such as Fe, Co, and / or Ni, and at least one Group VI metal (Column 6 of IUPAC periodic table), such as Mo and / or W, optionally supported on catalyst support comprising alumina, silica, silica-alumina, titania, zirconia, carbon, or a combination thereof.

[0055] Alternatively, the hydrotreating catalyst can be a bulk metal catalyst, or a combination of stacked beds of supported and bulk metal catalyst. The term bulk metal catalyst means that the catalysts are unsupported. The bulk metal catalyst comprises 30wt.% - 100 wt.% of at least one Group VIII non-noble metal and at least one Group VLB metal, based on the total weight of the bulk metal catalyst, calculated as metal oxides. The bulk metal catalysts (also referred to as “bulk metal hydrotreating catalysts”) have a surface area of at least 10 m2 / g. In an embodiment, the bulk metal hydrotreating catalyst can comprise about 50 wt.% to about 100 wt.%, and about 70 wt.% to about 100 wt.%, of at least one Group VIII non-noble metal and at least one Group VLB metal, based on the total weight of the catalyst, calculated as metal oxides.

[0056] Bulk metal hydrotreating catalysts have a surface area of at least 50 m2 / g, and at least 100 m2 / g. The pore size distribution of the bulk metal hydrotreating catalysts are approximately the same as a conventional hydrotreating catalyst. Bulk metal hydrotreating catalysts have a pore volume of 0.05 ml / g to 5.0 ml / g, or 0.1 ml / g to 4 ml / g, 0.1 ml / g to 3 ml / g,2024EM157-US and 0.1 ml / g to 2 ml / g determined by nitrogen adsorption. Typically, pores smaller than 1 nm are not present. The bulk metal hydrotreating catalysts have a median diameter of at least 50 nm, or at least 100 nm. The bulk metal hydrotreating catalysts can have a median diameter of not more than 5,000 pm, or not more than 3,000 pm. In an embodiment, the median particle diameter of the bulk metal hydrotreating catalyst is in the range of 0.1 pm - 50 pm and most preferably in the range of 0.5 pm - 50 pm.

[0057] Various configurations for hydrocracking and hydrotreating are described in US Pat. No. 9,302,472, Col. 7. 1. 15 to Col. 9, 1. 21 incorporated by reference.

[0058] In an embodiment, the liquid plastic waste is a pyrolysis oil (referred herein as a “pyoil”). In an embodiment, the pyoil is hydrotreated with a hydrotreating catalyst to remove halogen, oxygen, and nitrogen from the pyoil at a pressure between 100 psig and 2,000 psig of H2, a temperature between 350°C and 550°C at a liquid hourly space velocity between 0.1 and 10 g pyoil / g catalyst / hour. The hydrotreating catalyst comprises CoMo, CoW, NiMo, NiW, Fe, Pt, Ru, Au, Rh, Ir, Ru, or a combination thereof, optionally supported on catalyst support comprising alumina, silica, silica-alumina, titania, zirconia, carbon, or a combination thereof.Steam Cracking

[0059] Steam cracking is used to produce light olefins. In typical steam cracking processes, the hydrocarbon feed is first preheated and mixed with dilution steam in the convection section of the furnace. After preheating in the convection section, the vapor feed / dilution steam mixture is rapidly heated in the radiant section to achieve the desired thermal cracking. After the desired degree of thermal cracking has been achieved in the radiant section, the furnace effluent is rapidly quenched in either an indirect heat exchanger or by the direct injection of a quench oil stream.

[0060] A typical steam cracking furnace is described in US Pub. App. No. 2018 / 0170832

[0014] , Steam cracking can be used for the conversion of various types of hydrocarbon feed materials rich in aliphatic hydrocarbons into lighter hydrocarbons rich in olefins. To that extent, in the present methods, the hydrocarbon material fed into the furnace contain ethane as a major component. For example, the fresh hydrocarbon material can contain, by weight of the total fresh feed, from al% to a2%, of ethane, where al and a2 can be, independently, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, as long as al<a2.

[0061] Alternatively, the hydrocarbons fed into the furnace can contain butane as a major component. For example, the fresh hydrocarbon material can contain, by weight of the total fresh feed, from bl% to b2%, of butane, where bl and b2 can be, independently, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, as long as bl<b2.2024EM157-US

[0062] Typically, the heavier the hydrocarbon material fed into the steam cracking furnace, the lower the operation temperature, and the heavier the cracked fluid mixture tends to be. As indicated above, the process of the present invention can be used for steam cracking of various hydrocarbon materials as fresh feed, to obtain different cracked products, particularly olefins with different molecular sizes.

[0063] In general, in the process of the present invention, temperature at the lower portion of the convection zone, particularly at the end thereof (Tl), is controlled at sufficiently high, such that significant cracking reactions occur in the lower portion of the convection section and the cross-over section before the second fluid stream enters into the radiant section, where a great majority of the steam cracking take place. Thus, compared to the feed mixture including all fresh feed, recycled hydrocarbon, and steam assuming no chemical reactions having taken place, the first fluid mixture exiting the end of the convection section and entering the crossover section tends to have an overall olefins concentration. Thus, assuming the feed comprises olefins at a total concentration of CO mol % based on the total moles of the fluid species in the feed before any cracking reaction occurs; the first fluid stream comprises olefins at a total concentration of Cl mol % based on the total moles of the fluid species therein; then gl%<Cl-C0<g2%, where gl and g2 can be, independently, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, as long as gl<g2.

[0064] As indicated above, typically T2<T1<T3. Where the cross-over section is not actively heated and merely thermally insulated outside of the furnace box, due to the endothermal nature of the cracking reactions, the temperature of the fluid stream inside the cross-over section decreases from the beginning to the end. Thus, the temperature differential T1-T2 can be in the range from el to e2°F, where el and e2 can be, independently, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or even 5, as long as el<e2. In the cross-over section of the reactor, additional cracking is allowed to continue because of the relatively high temperature Tl of the first fluid mixture entering the cross-over section, even if T2<T1. Thus, assuming the feed comprises olefins at a total concentration of CO mol% based on the total moles of the fluid species in the feed before any cracking reaction occurs; the second fluid stream comprises olefins at a total concentration of C2 mol% based on the total moles of the fluid species therein; then hl%<C2-C0<h2%, where hl and h2 can be, independently, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, as long as hl<h2.

[0065] The temperature differential T3-T2 can be in the range from fl to f2°F, where fl and f2 can be, independently, 100, 150, 200, 250, 300, 350, 400, 450, or 500, as long as fl<f2. This significantly higher T3 would lead to a majority of the cracking reactions in the radiant2024EM157-US sections even though the residence time therein is typically very short, e.g., on the order of milliseconds to hundreds of milliseconds.

[0066] The cracking conditions, especially those in the radiant section, are chosen to favor the thermal pyrolysis of the aliphatic hydrocarbon molecules in the feed material to produce smaller, unsaturated hydrocarbon molecules and hydrogen in the cracked fluid mixture. The unsaturated hydrocarbons tend to have higher economic value than the aliphatic feed and are used as industrial raw materials for making additional materials such as polymers.

[0067] At the end of the radiant section, the cracked fluid mixture is typically quenched immediately by a heat exchanger or by the injection of a quenching fluid stream. The quenched fluid stream is at a temperature where significant chemical reactions between and among the chemical species in the cracked fluid mixture is substantially stopped, preventing the formation of undesirable compounds that may form coke. The cracked fluid mixture can be separated in a downstream vessel by conventional methods such as condensation and evaporation to obtain various fractions: hydrogen, desirable unsaturated hydrocarbon fractions, and residual aliphatic hydrocarbons. The residual aliphatic hydrocarbons may be recycled into the steam cracking reactor, where it is further converted into desirable products, or alternatively, it may be combusted as a fuel for, e.g., producing the flames that heat the steam cracking furnace, particularly the radiant section.Ethane Steam Cracking

[0068] For ethane cracking, an ethane feed to the steam cracking reactor comprises from 50-100 mol% (e.g., 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, 100 mol%) of ethane. As a minor component, propane may be present in the total hydrocarbon feed material as well, e.g., at a concentration from 5% to 50% by mole (e.g., 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 mol %) of the total hydrocarbon feed. Under the cracking conditions, especially in the radiant section where the temperature is high, the cracking of ethane and propane are favored to produce methane, ethene, propene, hydrogen, acetylene, methylacetylene, which are smaller in molecular weight than ethane and / or propane. Larger molecules, such as C4, C5, and C6 hydrocarbons, may be produced as well, but typically at low concentrations. Upon separation in down-stream processes, C4, C5, and C6 olefins and aromatics can be obtained as valuable byproducts, and residual ethane and propane can be recycled to the steam cracking furnace as a portion of the overall feed.

[0069] Tf can be in the range from Tf (ethane) f to Tf (ethane) 2°F, where Tf (ethane) f and Tf(ethane)2 can be, independently, f300, 1325, 1350, 1375, f400, f405, 1410, 1415, f420, f425, f430, 1435, as long as Tf (ethane) f<Tf(ethane)2;2024EM157-US

[0070] T2 can be in the range from T2(ethane)l to T2(ethane)2°F, where T2(ethane)l and T2(ethane)2 can be, independently, 1275, 1300, 1325, 1350, 1375, 1400, 1410, 1420, 1430, as long as T2(ethane)l<T2(ethane)2; and

[0071] T3 can be in the range from T3 (ethane) 1 to T3(ethane)2°F, where T3 (ethane) 1 and T3(ethane)2 can be, independently, 1500, 1525, 1550, 1575, 1600, 1625, 1650, 1675, 1700, 1725, 1750, 1775, 1800, as long as T3 (ethane) l<T3(ethane)2.

[0072] The conversion of ethane in the process of the present invention can be desirably high, generally higher than 50% and lower than 80%. At higher than 80%, the selectivity toward ethene can be low. Thus, the conversion of ethane can be from Con(l)% to Con(2)%, where Con(l) and Con(2) can be, independently, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, as long as Con(l)<Con(2).

[0073] In the steam cracking process of the present invention for ethane, it is highly desirable that the total concentration of C5 and C6 olefins, dienes and benzene in the cracked fluid mixture is in a range from xl mol % to x2 mol % based on the total moles of different species therein, where xl and x2 can be, independently, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0, as long as xl<x2.

[0074] In the steam cracking process of the present invention for ethane, it is highly desirable that process has a total severity index (SI) in the cracked fluid mixture in a range from si to s2, where si and s2 can be, independently, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, as long as sl<s2.Dehydrogenation of Propane

[0075] Catalytic dehydrogenation of paraffinic hydrocarbons to olefinic hydrocarbons, and / or lower alkylaromatic hydrocarbons to vinyl aromatic hydrocarbons is described generally in US Pat. No. 8,653,317. Exemplary dehydrogenation process is specifically described in US Pat. No. 8,654,317 at Col. 8, 1. 39 to Col. 9, 1. 52 incorporated by reference.

[0076] Generally, dehydrogenation of lower alkanes comprises contacting a gaseous stream of hydrocarbon with a dehydrogenation catalyst at reaction temperature over a relatively short "contact time." In the dehydrogenation process, lower alkanes, for example ethane, propane and butanes are dehydrogenated to their corresponding olefins, for example ethylene, propylene and butylene.

[0077] Dehydrogenation catalysts for use in the present processes are very active and are capable of dehydrogenating paraffin and alkylaromatic hydrocarbons in less than a few seconds at ideal reaction temperatures. Generally, the dehydrogenation catalyst has a first component of tin, germanium, lead, indium, gallium, thallium or compounds thereof with an atomic ratio2024EM157-US to a second component of a Group 8 metal such as Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, or Pt within the range from 0.1 to 1000, 1 to 500, and from 1 to 200. An alkali metal or alkaline earth metal compound can also be present in an amount to provide from 0.0 to 2.0 percent, 0.1 to 1.0 percent metal, alkali metal in the catalyst. It is to be understood by the skilled artisan that other components besides the foregoing first and second components, alkali metal or alkaline earth metal, and support, are substantially or wholly absent. Typically, it is desirable not to have a detectable quantity of any non-recited component, especially manganese or zinc.

[0078] A dehydrogenation catalyst can be used as such or diluted with an inert material, for example, refractory oxides and other ceramics, such as metal- or metalloid-carbides, oxides or nitrides. Examples include silicon carbide and alumina having surface area of 50 m2 / g or less. The inert additive may be used at a concentration of the inert product of between 0 and 50 percent, preferably from 5 to 25 percent of the total catalyst.

[0079] Details on the preparation of hydrogenation catalysts suitable for use are described in US Pat. No. 8,653,317 as analogous to those employed in W02005 / 077867 (US-A- 2008 / 0194891), W02002 / 096844, (US Pat. No. 6,031,143, EP 0 905 112), US Pat. No. 6,031,143 and EP -B 1-0,637,578. Typically, the process of preparing the dehydrogenation catalysts comprises dispersing precursors of the catalytic metals, for example, solutions of soluble salts of the catalytic metals onto the preformed support. Suitable soluble salts particularly include the nitrate salts of the first component, especially gallium nitrate, and complexes of the Group 8 metal, such as tetraamineplatinum. More particularly, the foregoing process of dispersion can comprise impregnation of the carrier with one or more solutions containing the precursors of the first and second components, especially gallium and platinum, along with any other components, followed by drying and calcination. An alternative method comprises ion adsorption followed by the separation of the liquid portion of the adsorption solution, drying, and activation of the resultant solid. As another alternative, the carrier can be treated with volatile species of the desired metals. In the case of added alkali metals or alkaline earth metals, such compounds or their precursors may be added to the carrier prior to dispersion of the primary catalytic metals or compounds, followed, optionally, by calcination of the resulting solid. It will be understood by the skilled artisan that the actual species of each of the foregoing named components, under the conditions of their use as catalysts, may exist in the form of a compound, such as an oxide, and the metal or other component may be in an oxidation state other than that originally employed or designated herein.

[0080] A catalyst support is prepared by dehydration of soluble aluminum salts, especially aluminum hydroxides or mixtures thereof with aluminum oxides, and optionally silicates,2024EM157-US followed by heating in the presence of air to a temperature from 300°C to 800°C for time periods up to 24 hours. Additional compounds may optionally be present in the formulation in order to improve one or more physical properties of the support such as to increase abrasion resistance or decrease surface acidity. When silica is employed in the support, it is incorporated into the finished support by physically compounding it with the previously prepared alumina. Levels of silica incorporation are from 0.0% to 5.0%, and 0.0% to 2.0%. In an embodiment, microspheroidal pseudo-bohemite is prepared by spray drying hydrated alumina so to form particles suitably having an average particle size from 5 to 500 micrometers. This product is then heated to a temperature up to 800°C for a time for up to 8 hours. The drying may be accomplished in multiple steps at various temperatures to prevent loss of surface area. For example, the particles may be air dried at 350°C for 2 hours followed by heating at a temperature from 500°C to 800°C, 550°C to 700°C for up to 4 hours. As is well known in the art, heating pseudob ohemite to temperatures less than or equal to 800°C results in formation of the gamma alumina with substantially no formation of low surface area delta, theta or alpha crystalline phases, see, George J. Antos, et. al., ed., Catalytic Naphtha Reforming Science and Technology, Marcel Dekker, Inc., pg. 82, and M. Hill, et al., Chemistry of Materials (2007), v,19(ll) pp. 2877-2883.

[0081] In the present processes, the hydrocracked product comprises at least 70 wt.% ethane, less than 5 wt.% aromatics, propane and butane. Ethane is then steam cracked to ethylene, and propane is converted to propylene via dehydrogenation. In the present processes, ethane is separated from the hydrocracked product and converted to ethylene. Propane is separated from the hydrocracked product and converted to propylene. In an embodiment, ethane is steam cracked to provide ethylene. In an embodiment, propane is dehydrogenated catalytically to provide propylene. Butane and aromatics are saturated with hydrogen and a saturating catalyst to provide a saturated product. The saturated product is recycled and combined with the liquid plastic waste to make additional olefins.Saturation of Butanes and Aromatics

[0082] In the present processes, butanes and aromatics are conveniently saturated, without separation, at a pressure of between 100 psig and 2,000 psig of H2, a temperature of between 50°C and 350°C and a liquid hourly space velocity between 0.1 and 10 g feed / g catalyst / hour. In an embodiment, the saturating catalyst is selected from the group of Pt, Pd, Ir, Rh, Ru, or a combination thereof.

[0083] Hydrogenation processes are known in the petroleum industry to convert aromatic rich petroleum streams into naphthenes. Hydrogenation is typically performed at moderately2024EM157-US high hydrogen partial pressure over a non-noble metal catalyst such as Ni, Mo or a combination thereof, for deep hydrogenation, a noble metal catalyst such as Pt, Pd, Ir, Rh, Ru or a combination thereof.

[0084] The hydrogen stream may be obtained from any suitable source, for example pure hydrogen, hydrogen exiting from a reformer process or hydrogen obtained as a by-product from another refinery or chemical process. The hydrogen stream may be 100% hydrogen or may be diluted with another gas, for example light alkanes, carbon dioxide or an inert gas. Preferably the stream contains 5 vol% to 100 vol%, more preferably 30 vol% to 100 vol% hydrogen, and is typically fed into saturation reactor at a pressure of 100 psig - 2000 psig. Hydrogenation catalysts are well known and typically comprise 0.05 wt.% to 10 wt.%, preferably 0.1 wt.% to 2 wt.% of a metal such as platinum, palladium, ruthenium, rhodium, or iridium carried on a support comprising a zeolite or another support material such as a silica, alumina, titania or silica-alumina (including clays).

[0085] The hydrogenation is typically carried out at temperatures of 50°C - 350°C, or 25°C - 200°C; liquid hourly space velocity between 0.1 and 10 g feed / g catalyst / hour.; pressure 100 psig -2,000 psig; and a H2 to aromatics molar ratio of 0.1 : 1 to 10: 1. Under these conditions generally 90% to 100%, of the aromatics is converted to naphthenes such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane.

[0086] The saturated stream containing butanes and naphthenes is recycled to the hydrocracking reactor, which is hydrocracked together with the liquid plastic waste feed to a hydrocracked product comprising ethane and propane. Ethane and propane are separated and converted to ethylene and propylene respectively via the steam cracking or dehydrogenation disclosed above.

[0087] As described in the Examples below, the present process for catalytic conversion of a plastic waste to light olefins includes melting the plastic waste in the absence of oxygen to produce a liquid plastic waste. The liquid plastic waste is catalytically hydrocracked in the presence of hydrogen at a temperature of 600°C or less to produce the hydrocracked product comprising at least 70 wt.% ethane and less than 5 wt.% BTX. In the hydrocracker, hydrogen is mixed with the liquid plastic waste over the hydrocracking catalyst which in the Examples below was Pt / ZSM-5 catalyst. In the examples, the hydrocracking catalyst was a bifunctional catalyst comprising a metal function and an acid function. In an embodiment, the hydrocracking catalyst comprised a medium pore size zeolite having a free pore diameter of 0.45 nm to 0.6 nm and a metal function comprising Pt, Pd, Rh, Ru and Ir was used.2024EM157-US

[0088] As taught by the examples, ethane yield was increased by at least three-fold using a subsequent processing step of hydrocracking and in comparison with ethane yield of a thermal pyrolysis alone (flash pyrolysis) under the same process conditions.

[0089] Even more specifically, the conversion of plastic waste when subjected to mild pyrolysis followed by hydrocracking yielded a hydrocracked product with an amount of greater than 60 weight percent (“wt.%”) ethane, greater than 15 wt.% of propane; and less than 15 wt.% aromatics [BTX],

[0090] Aspects of the disclosure are described in greater detail by way of specific examples. The following examples are offered for illustrative purposes and are not intended to limit the disclosure in any manner. Those of skill in the relevant art will readily recognize a variety of parameters can be changed or modified to yield essentially the same results.Additional Embodiments

[0091] Embodiment 1. A process for conversion of a plastic waste to ethylene and propylene comprising the steps of: heating the plastic waste to provide a liquid plastic waste; hydrocracking the liquid plastic waste with hydrogen and a hydrocracking catalyst to produce a hydrocracked product comprising at least 70 wt.% ethane, less than 5 wt.% aromatics and propane and butanes; separating ethane from the hydrocracked product and converting ethane to ethylene; separating propane from the hydrocracked product and converting propane to propylene; and saturating butane and aromatics with hydrogen and a saturating catalyst to provide a saturated product, wherein the saturated product is recycled and combined with the liquid plastic waste to make additional olefins.

[0092] Embodiment 2. The process of embodiment 1, wherein said plastic waste comprises polyethylene, polypropylene, polystyrene, polyethylene terephthalate), poly(vinyl chloride), poly (vinyl dichloride), or a mixture thereof.

[0093] Embodiment 3. The process of embodiment 1, wherein the plastic waste is heated at a temperature of between 250°C and 550°C.

[0094] Embodiment 4. The process of embodiment 1, wherein the liquid plastic waste is a pyrolysis oil (pyoil).

[0095] Embodiment 5. The process of embodiment 4, wherein the pyoil is hydrotreated with a hydrotreating catalyst to remove halogen, oxygen, and nitrogen from the pyoil.2024EM157-US

[0096] Embodiment 6. The process of embodiment 5, wherein the pyoil is hydrotreated at a pressure between 100 psig and 2,000 psig of EE, a temperature between 350°C and 550°C and at a liquid hourly space velocity between 0.1 g and 10 g pyoil / g catalyst / hour.

[0097] Embodiment 7. The process of embodiment 5, wherein the hydrotreating catalyst comprises CoMo, CoW, NiMo, NiW, Fe, Pt, Ru, Au, Rh, Ir, Ru or a combination thereof.

[0098] Embodiment 8. The process of embodiment 1, wherein hydrocracking is performed at a pressure between 100 psig and 2,000 psig of Ek and a temperature of between 350°C and 600°C.

[0099] Embodiment 9. The process of embodiment 8, wherein the hydrocracking catalyst comprises a metal function and an acid function and operates at a liquid hourly space velocity of between 0.1 g and 10 g feed / g catalyst / hour.

[0100] Embodiment 10. The process of embodiment 9, where the metal function comprises Pt, Pd, Ir, Ni, Rh, Ir, Ru or a combination thereof and the acid function comprises a zeolite selected from MFI, MOR, FAU, MWW, BEA, or a combination thereof.

[0101] Embodiment 11. The process of embodiment 9, where the hydrocracking catalyst is selected from the group of Pt / MFI, Pt / MOR, Pt / FAU, Pt / BEA, or Pt-Ir / MFI.

[0102] Embodiment 12. The process of embodiment 1, wherein butanes and aromatics are saturated at a pressure of between 100 psig and 2,000 psig of Ek, a temperature of between 50°C and 350°C and a liquid hourly space velocity between 0.1 g and 10 g feed / g catalyst / hour.

[0103] Embodiment 13. The process of embodiment 12, wherein the saturating catalyst is selected from the group of Pt, Pd, Ir, Rh, Ir, Ru or a combination thereof.

[0104] Embodiment 14. The process of embodiment 1, wherein ethane is steam cracked to provide ethylene.

[0105] Embodiment 15. The process of embodiment 1, wherein propane is dehydrogenated catalytically to provide propylene.

[0106] Embodiment 16. A process for conversion of a plastic waste comprising the steps of: heating the plastic waste to a temperature of 550°C or less to provide a pyoil; and hydrocracking the pyoil with hydrogen in the presence of a hydrocracking catalyst selected from the group of Pt / ZSM-5, Pt / MOR, Pt / FAU, and Pt / BEA at a pressure between 100 psig and 2,000 psig of Ek, and at a temperature between 350°C and 600°C, wherein the plastic waste is cracked to produce a hydrocracked product comprising greater than 50 wt.% ethane, greater than 15 wt.% propane and less than 5 wt.% aromatics.2024EM157-US

[0107] Embodiment 17. The process of embodiment 16, further comprising the step of steam cracking ethane to produce ethylene.

[0108] Embodiment 18. The process of embodiment 16, further comprising the step of dehydrogenating propane to produce propylene.

[0109] Embodiment 19. The process of embodiment 16, wherein the hydrocracked product further comprises butanes and aromatics and the butanes and aromatics are saturated at a pressure of between 100 psig and 2,000 psig of H2, at a temperature between 50°C and 350°C and in the presence of a saturating catalyst selected from Pt-Pd, Pt-Ir, or Ir-Rh to provide a recycle feed stream for hydrocracking with the pyoil.EXAMPLES

[0110] Pyrolysis and hydrocracking experiments were performed in a modified tandem pyrolyzer-catalytic reactor unit. The pyrolyzer-catalytic reactor unit comprises two reactors connected in tandem. The first reactor was a micro-pyrolyzer and the second reactor was used as a cracking unit. The first reactor and the second reactor were independently temperature controlled, allowing for evaluation of pyrolysis and subsequent cracking at different temperatures.[OHl] In the experiment, the pyrolyzer-catalytic reactor unit was positioned on top of a GC / MSD / FID instrument (Agilent). Approximately 0.5 mg of plastic waste sample was loaded in a SS metal cup, which was dropped in the first reactor (pyrolyzer) at a pre-set temperature. Products of the first reactor are swept by helium (60 seem) into the second reactor (for thermal or catalytic cracking).

[0112] For evaluation of hydrocracking, Ek was introduced to the second reactor and mixed with a pyrolysis stream and was reacted over the hydrocracking catalyst. The effluent from the second reactor was trapped (at -195°C) via a micro-jet cooled with liquid nitrogen. After a predetermined sample trapping period (5 minutes), the trapped reaction sample is warmed up and travels through the GC column for separation. The effluent from the GC column is split 3 / 1 (v / v) and sent to a flame ionization detector (FID, for quantification) and mass spec detector (MSD, for identification), respectively.

[0113] For separation, a 30 m x 0.25 mm x 0.1 pm DB-5HT column (Agilent J&W) was used. The GC conditions included: helium carrier gas, 1.4 cc / min column flow; 25 / 1 split ratio; temperature: 35°C initial (5-minute hold), ramping to 200°C at 7.5°C / min and then to 325°C at 20°C / min and hold for 10 minutes. H2, if formed, cannot be trapped using the micro-jet and therefore is not detected using this technique.2024EM157-US

[0114] The GC oven temperature profile was optimized for heavy product separation, thereby resolution for the light end is somewhat comprised: methane / ethane / ethylene co-elude, and similarly, propylene / propane, butenes / butanes also co-elude. However, based on the mass spectra, the amounts of alkane formed from the examples are low.Example 1Flash Pyrolysis and Mild Pyrolysis of LLDPE

[0115] In this experiment, LLDPE (Exceed 1018) was subject to flash pyrolysis (“FP”) at 700°C while the second reactor was packed with quartz chips and held at 250°C. The second reactor packed with quartz chips was then held at 500°C for mild pyrolysis (“MP”). Methane (very small amount), C2-C4 olefins, C5+ dienes, and BTX (lumped in the C5-C8 fraction) are the primary products under these thermal pyrolysis conditions. Yields of C2-C4 olefins were both low. FIG. 1.Example 2Flash Pyrolysis of LLDPE and Cracking Using Pt / ZSM-5 Catalyst in Absence of H2

[0116] In this experiment, LLPDE (Exceed 1018) was subject to flash pyrolysis followed by cracking using Pt / ZSM-5 catalyst in the absence of H2. The LLPDE was subject to flash pyrolysis at 700°C FP followed by cracking in the absence of hydrogen with a Pt / ZSM-5 catalyst at 500°C. In a comparative, LLPDE was subject to flash pyrolysis at 700°C while the second reactor was packed with quartz chips and held at 250°C. The amounts of C2 (predominantly ethylene) and C5-C8 increased with Pt / ZSM-5 catalyst in the absence of H2. However, there was also an increase in aromatics which is undesired in the context of light olefin production. FIG. 2.Example 3Mild Pyrolysis of LLDPE With Hydrocracking with a Pt / ZSM-5 Catalyst in the Presence of H2

[0117] In this experiment, LLPDE (Exceed 1018) was subject to mild pyrolysis at 550°C followed by hydrocracking with 20% H2 in He at 600°C. Also, LLPDE (Exceed 1018) was subject to mild pyrolysis at 550°C followed by hydrocracking with 20% H2 in He at 550°C. Finally, LLPDE (Exceed 1018) was subject to mild pyrolysis at 550°C followed by hydrocracking with 20% H2 in He at 500°C. The hydrocracked products produced were predominantly ethane (greater than 80%) with yields to propane (less than 5%) and aromatics (less than 12%) that were very low. FIG. 3.2024EM157-USExample 4Mild Pyrolysis of Plastics and Hydrocracking Using Pt / ZSM-5 Catalyst in the Presence of H2

[0118] In this experiment, different plastics were converted to a hydrocracked product using the mild pyrolysis (550°C) coupled with hydrocracking with 20% H2 in He, 600°C. The plastics included: LLDPE (PEI 018); HDPE (XP1000); PP; PS; and PET. Clearly the present processes convert polyolefins to predominantly ethane / propane. FIG. 4. For polystyrene and poly(ethylene terephthalate), ethane and propane were also formed. However, the aromatic core can be saturated, ring-opened, and hydro-cracked to light ethane / propane under higher pressure of H2.

Claims

2024EM157-USCLAIMSWe claim:

1. A process for conversion of a plastic waste to ethylene and propylene comprising the steps of: heating the plastic waste to provide a liquid plastic waste; hydrocracking the liquid plastic waste with hydrogen and a hydrocracking catalyst to produce a hydrocracked product comprising at least 70 wt.% ethane, less than 5 wt.% aromatics and propane and butanes; separating ethane from the hydrocracked product and converting ethane to ethylene; separating propane from the hydrocracked product and converting propane to propylene; and saturating butane and aromatics with hydrogen and a saturating catalyst to provide a saturated product, wherein the saturated product is recycled and combined with the liquid plastic waste to make additional olefins.

2. The process of claim 1, wherein said plastic waste comprises polyethylene, polypropylene, polystyrene, polyethylene terephthalate), poly(vinyl chloride), poly (vinyl dichloride), or a mixture thereof.

3. The process of claim 1, wherein the plastic waste is heated at a temperature of between 250°C and 550°C.

4. The process of claim 1, wherein the liquid plastic waste is a pyrolysis oil (pyoil).

5. The process of claim 4, wherein the pyoil is hydrotreated with a hydrotreating catalyst to remove halogen, oxygen, and nitrogen from the pyoil.

6. The process of claim 5, wherein the pyoil is hydrotreated at a pressure between 100 psig and 2,000 psig of H2, a temperature between 350°C and 550°C and at a liquid hourly space velocity between 0.1 g and 10 g pyoil / g catalyst / hour.

7. The process of claim 5, wherein the hydrotreating catalyst comprises C0M0, CoW, NiMo, NiW, Fe, Pt, Ru, Au, Rh, Ir, Ru or a combination thereof.

8. The process of claim 1, wherein hydrocracking is performed at a pressure between 100 psig and 2,000 psig of H2 and a temperature of between 350°C and 600°C.2024EM157-US9. The process of claim 8, wherein the hydrocracking catalyst comprises a metal function and an acid function and operates at a liquid hourly space velocity of between 0.1 g and 10 g feed / g catalyst / hour.

10. The process of claim 9, where the metal function comprises Pt, Pd, Ir, Ni, Rh, Ir, Ru or a combination thereof and the acid function comprises a zeolite selected from MFI, MOR, FAU, MWW, BEA, or a combination thereof.

11. The process of claim 9, where the hydrocracking catalyst is selected from the group of Pt / MFI, Pt / MOR, Pt / FAU, Pt / BEA, or Pt-Ir / MFI.

12. The process of claim 1, wherein butanes and aromatics are saturated at a pressure of between 100 psig and 2,000 psig of Ek, a temperature of between 50°C and 350°C and a liquid hourly space velocity between 0.1 g and 10 g feed / g catalyst / hour.

13. The process of claim 12, wherein the saturating catalyst is selected from the group of Pt, Pd, Ir, Rh, Ir, Ru or a combination thereof.

14. The process of claim 1, wherein ethane is steam cracked to provide ethylene.

15. The process of claim 1, wherein propane is dehydrogenated catalytically to provide propylene.

16. A process for conversion of a plastic waste comprising the steps of: heating the plastic waste to a temperature of 550°C or less to provide a pyoil; and hydrocracking the pyoil with hydrogen in the presence of a hydrocracking catalyst selected from the group of Pt / ZSM-5, Pt / MOR, Pt / FAU, and Pt / BEA at a pressure between 100 psig and 2,000 psig of H2, and at a temperature between 350°C and 600°C, wherein the plastic waste is cracked to produce a hydrocracked product comprising greater than 50 wt.% ethane, greater than 15 wt.% propane and less than 5 wt.% aromatics.

17. The process of claim 16, further comprising the step of steam cracking ethane to produce ethylene.

18. The process of claim 16, further comprising the step of dehydrogenating propane to produce propylene.2024EM157-US19. The process of claim 16, wherein the hydrocracked product further comprises butanes and aromatics and the butanes and aromatics are saturated at a pressure of between 100 psig and 2,000 psig of H2, at a temperature between 50°C and 350°C and in the presence of a saturating catalyst selected from Pt-Pd, Pt-Ir, or Ir-Rh to provide a recycle feed stream for hydrocracking with the pyoil.

Images